Helicobacter pylori: análisis de cagA y genotipificación de vacA en Chile. Detección de una cepa s2/m1

Martínez, Angie Carolina Neira; González, Carlos; Kawaguchi, Fernando Aparecido; Montoya, Rolando; Corvalán, Alejandro; Madariaga, Juan Andrés; Roa, J. J.; García, Antonio Manuel Rodríguez; Salgado, Fernando; Solar, Henry; Palma, Marc Di

doi:10.4067/s0034-98872001001000006

Cited by 17 publications

(10 citation statements)

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“…Wild-type H. pylori strains of vacA type s2/m1 have only rarely been isolated (32,55,56), and we have identified only one that expresses VacA. Population genetic analyses show that vacA structure is characterized by frequent recombination events between vacA from different strains (57)(58)(59)(60), so vacA s2/m1 structures would be expected to arise in vivo as frequently as s1/m2 structures.…”

Section: Discussionmentioning

confidence: 99%

“…However, such strains comprise only about 40% of strains isolated from patients undergoing endoscopy (31)(32)(33)(34)(35)(36)(37)(38), and this proportion would be expected to be smaller in an unselected population. We have now concentrated on the s2/m2 type of VacA found in non-pathogenic, non-toxigenic strains and the common hybrid s1/m2 type and uncommon hybrid s2/m1 type (32,55,56). We have shown that strains with the type s2 signal region are non-vacuolating due directly to the N-terminal extension on the mature toxin of these strains.…”

Section: Discussionmentioning

confidence: 99%

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Determinants of Non-toxicity in the Gastric Pathogen Helicobacter pylori

Letley

Rhead

Twells

et al. 2003

Journal of Biological Chemistry

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The Helicobacter pylori vacuolating cytotoxin gene, vacA, is naturally polymorphic, the two most diverse regions being the signal region (which can be type s1 or s2) and the mid region (m1 or m2). Previous work has shown which features of vacA make peptic ulcer and gastric cancer-associated type s1/m1 and s1/m2 strains toxic. vacA s2/m2 strains are associated with lower peptic ulcer and gastric cancer risk and are non-toxic. We now define the features of vacA that determine the nontoxicity of these strains. To do this, we deleted parts of vacA and constructed isogenic hybrid strains in which regions of vacA were exchanged between toxigenic and non-toxigenic strains. We showed that a naturally occurring 12-amino acid hydrophilic N-terminal extension found on s2 VacA blocks vacuolating activity as its removal (to make the strain s1-like) confers activity. The mid region of s2/m2 vacA does not cause the non-vacuolating phenotype, but if VacA is unblocked, it confers cell line specificity of vacuolation as in natural s1/m2 strains. Chromosomal replacement of vacA in a nontoxigenic strain with vacA from a toxigenic strain confers full vacuolating activity proving that this activity is entirely controlled by elements within vacA. This work defines why H. pylori strains with different vacA allelic structures have differing toxicity and provides a rational basis for vacA typing schemes.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Determinants of Non-toxicity in the Gastric Pathogen Helicobacter pylori

Letley

Rhead

Twells

et al. 2003

Journal of Biological Chemistry

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“…Nuestro grupo de investigación está abocado a caracterizar cepas de H pylori que infectan a pacientes locales, en base a genes de virulencia de importancia reconocida por su asociación con patologías gastroduodenales severas 23,29 . También contamos con información patofisiológica útil, que puede tener implicancias clínicas significativas 30 , pues estudios de poblaciones de oriente y occidente señalan que los factores de virulencia de H pylori varían de acuerdo a la localidad geográfica y a la edad del individuo 31 .…”

Section: Discussionunclassified

“…A pesar de la elevada prevalencia de infección por H pylori en nuestro país, aún son pocos los trabajos en genotipificación de cepas incluyendo los genes cagA y vacA [23][24][25] y no se encuentran trabajos con respecto al gen babA2.…”

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Genotipificación de aislados clínicos de Helicobacter pylori en base a genes asociados a virulencia cagA, vacA y babA2: Primer aislamiento de una cepa babA2 positiva en pacientes chilenos

C¹,

T²,

Sch³

et al. 2006

Rev. méd. Chile

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“…Nonetheless, previous results published by our research group (29) indicate that (30), therefore, type I strains of H pylori may be partially responsible for the histopathological finding among Chilean patients. However, we cannot rule out the possibility that simultaneous infection with more than one genotype of H. pylori could play a role in damage severity, because it has been seen that a fraction of Chilean population is infected by two or more H. pylori genotype (31).…”

Section: Discussionmentioning

confidence: 99%

Low co-existence rates of Lactobacillus spp. and Helicobacter pylori detected in gastric biopsies from patients with gastrointestinal symptoms

García

Sáez

Delgado

et al. 2012

Rev. esp. enferm. dig.

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Background: bacterial diversity of the stomach includes various species. Among them, Helicobacter pylori, a microorganism which has been associated to gastric diseases, is frequently isolated in this habitat. In addition, Lactobacillus spp., a genus including probiotic strains, has also been documented in this habitat. The co-existence of these two species in the stomach of symptomatic patient needs to be elucidated.Aims: our goal was to establish if Lactobacillus spp. and H. pylori co-exist in the stomach mucosa of symptomatic patients.Methods: gastric biopsies (antrum and/or the body) from 427 Chilean patients with gastrointestinal discomfort were analyzed. The H. pylori infection and/or Lactobacillus spp. colonization status was determined for each patient by standard culture techniques, and statistical correlations between the presence of those species and the age, gender, or the severity of the gastric disease were also established.Results: only 6.1% of the samples presented co-existence of Lactobacillus spp. and H. pylori. This former species was isolated in 42.6% of the patients as unique species, while Lactobacillus spp. was isolated as single species in 19.4% of the individuals. Chronic non-atrophic gastritis was prevalent in Lactobacillus spp. non colonized individuals, while chronic non-atrophic and chronic atrophic gastritis diagnosis was similar in Lactobacillus spp. harbouring individuals (p < 0.001). The presence of Lactobacillus spp. significantly increased with age (p = 0.005), independently of gender.Conclusion: the negative Pearson correlation between Lactobacillus spp. and H. pylori (r = -0.112, p = 0.020) indicates that the co-existence of both species is low in human gastric mucosa of symptomatic patients.

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Helicobacter pylori: análisis de cagA y genotipificación de vacA en Chile. Detección de una cepa s2/m1

Cited by 17 publications

References 0 publications

Determinants of Non-toxicity in the Gastric Pathogen Helicobacter pylori

Determinants of Non-toxicity in the Gastric Pathogen Helicobacter pylori

Genotipificación de aislados clínicos de Helicobacter pylori en base a genes asociados a virulencia cagA, vacA y babA2: Primer aislamiento de una cepa babA2 positiva en pacientes chilenos

Low co-existence rates of Lactobacillus spp. and Helicobacter pylori detected in gastric biopsies from patients with gastrointestinal symptoms

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